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Triage and Emergency Assessment

When several patients arrive at once and there is one of you, the most important clinical skill is not any single intervention — it is deciding who is seen first and what could kill this person in the next few minutes. Triage and emergency assessment are the twin disciplines that answer those questions. Triage sorts a crowd by acuity so limited resources go where they save the most life; emergency assessment is the structured, repeatable sweep — the ABCDE primary survey followed by a head-to-toe secondary survey — that finds and fixes immediate threats in a fixed order.

For a nurse, this is high-stakes, high-frequency work. Getting the order right turns chaos into a plan and prevents the classic error of fixing something visible and dramatic (a broken, bleeding leg) while missing something silent and lethal (an obstructed airway). This page teaches both the sorting systems and the assessment framework the way experienced emergency and critical-care nurses actually use them.

Learning Objectives​

  • Explain the purpose of triage and describe the major triage systems (ESI, CTAS, MTS, START).
  • Perform the primary survey using the ABCDE approach and identify immediately life-threatening findings at each step.
  • Distinguish the primary survey from the secondary survey and know when to move on versus stop and treat.
  • Apply triage acuity levels to realistic patient scenarios and justify the assigned priority.
  • Recognize common triage and assessment errors and the corrections that prevent patient harm.

Quick Answer​

Triage is the process of rapidly sorting patients by clinical urgency so the sickest are treated first when resources are limited. Modern departments use validated systems such as the 5-level Emergency Severity Index (ESI), the Canadian Triage and Acuity Scale (CTAS), or the Manchester Triage System (MTS); mass-casualty scenes use START. Emergency assessment begins with the primary survey — ABCDE (Airway, Breathing, Circulation, Disability, Exposure) — a strict sequence in which each life threat is treated before moving on. Only once the patient is stable does the secondary survey follow: a focused history and complete head-to-toe examination to find everything else. The guiding rule is "treat first what kills first," and any deterioration means you go back to A and start again.

Where It Came From​

Triage was born of scarcity on the battlefield. The word comes from the French trier, "to sort." Baron Dominique Jean Larrey, Napoleon's surgeon-in-chief in the early 1800s, made two radical decisions: he created "flying ambulances" (ambulances volantes) to bring the wounded off the field quickly, and — crucially — he insisted that soldiers be treated in order of the severity and urgency of their wounds, regardless of rank or nationality. Before Larrey, officers were treated first and the wounded often waited on the field until fighting stopped. His need was brutally practical: too many casualties, too few surgeons, and the knowledge that speed changed who lived.

The idea matured through later wars. The World Wars and especially the Korean and Vietnam conflicts refined the link between rapid sorting, rapid transport, and survival — the origin of the "golden hour" concept popularized by trauma surgeon R Adams Cowley, who argued that survival from major trauma falls sharply if definitive care is delayed. Military mobile surgical hospitals (MASH units) proved that structured sorting plus fast evacuation saved lives at scale.

Civilian medicine then borrowed the battlefield lesson. As emergency departments grew crowded in the late 20th century, hospitals needed a consistent way to decide who could wait. The ABCDE primary survey was formalized by the Advanced Trauma Life Support (ATLS) course, launched in 1978 in the United States after an orthopedic surgeon, James Styner, crashed his private plane, and he and his injured family received poor, disorganized emergency care. His outrage — "when I can provide better care in the field with limited resources than what my children and I received at the primary care facility, there is something wrong with the system" — drove the creation of a standardized, order-of-priority approach that is now taught worldwide. So both halves of this topic — sorting and systematic assessment — grew from the same need: too many patients or too little time, and the discovery that a fixed, priority-based process saves more lives than improvisation.

Triage Systems: Sorting by Acuity​

Triage assigns each patient an acuity level that determines how quickly they must be seen. Most modern emergency departments use a validated 5-level scale, which research shows predicts resource use, admission, and mortality far better than older 3-level ("emergent/urgent/non-urgent") systems.

Emergency Severity Index (ESI) — the dominant system in the United States. It is algorithm-driven and blends acuity with expected resource needs:

  • ESI-1: Requires immediate life-saving intervention (e.g., apneic, pulseless, unresponsive, severe respiratory distress). See now.
  • ESI-2: High-risk situation, or confused/lethargic/severe pain, or dangerous vital signs (e.g., chest pain suggestive of MI, stroke symptoms, suicidal ideation). Should not wait.
  • ESI-3, 4, 5: Stable patients, sorted by how many resources they will likely need (labs, imaging, IV meds, consults). ESI-3 = two or more resources, ESI-4 = one, ESI-5 = none (e.g., a simple prescription refill or suture removal).

Canadian Triage and Acuity Scale (CTAS): Five levels tied to target time-to-physician — Level 1 (Resuscitation, immediate), Level 2 (Emergent, 15 min), Level 3 (Urgent, 30 min), Level 4 (Less urgent, 60 min), Level 5 (Non-urgent, 120 min).

Manchester Triage System (MTS): Common in the UK and Europe; uses flowcharts based on presenting complaint and "discriminators" to assign a color/priority (Red-immediate, Orange-very urgent, Yellow-urgent, Green-standard, Blue-non-urgent).

START (Simple Triage And Rapid Treatment): Used at mass-casualty incidents, not the everyday ED. It is designed for one provider to sort many victims in under 60 seconds each using Respirations, Perfusion, and Mental status (RPM), assigning color tags: Red (immediate), Yellow (delayed), Green (minor/walking wounded), Black (deceased/expectant). The philosophy inverts everyday care: the goal is the greatest good for the greatest number, so an unsalvageable patient (black) is passed over to save several who are recoverable.

Worked triage example. A 58-year-old man walks to the desk clutching his chest, diaphoretic, saying the pain radiates to his jaw and started 20 minutes ago. Vitals: HR 104, BP 158/92, SpO2 96%. He is not currently dying (so not ESI-1), but this is a high-risk presentation (possible acute MI) — assign ESI-2. He must go straight to a monitored bed for ECG within 10 minutes, not to the waiting room, even though he is talking and walking.

The Primary Survey: ABCDE​

The primary survey is a rapid (often under 60 seconds initially) systematic search for immediate life threats, done in strict order because the sequence reflects how quickly each problem kills. You do not proceed to B until A is secured. If the patient deteriorates at any point, you return to A.

  • A — Airway (with cervical-spine protection in trauma). Is the airway patent? Can the patient speak clearly? Listen for stridor, gurgling, or snoring; look for foreign bodies, blood, vomit, or swelling. Interventions: chin-lift/jaw-thrust (jaw-thrust if C-spine injury suspected), suction, oropharyngeal/nasopharyngeal airway, or advanced airway. A silent patient who cannot speak is an emergency.
  • B — Breathing and ventilation. Assess rate, depth, symmetry, work of breathing, SpO2, breath sounds. Look for life threats: tension pneumothorax, open ("sucking") chest wound, flail chest, massive hemothorax. Interventions: high-flow oxygen, bag-valve-mask ventilation, needle decompression for tension pneumothorax, occlusive dressing for open wound.
  • C — Circulation with hemorrhage control. Check pulse (rate, quality), skin (color, temperature, capillary refill), and look for major bleeding. In trauma, external hemorrhage control comes first — direct pressure, tourniquet. Interventions: two large-bore IVs, fluids/blood, control bleeding. Signs of shock (tachycardia, cool clammy skin, delayed cap refill, falling BP — remember hypotension is often a late sign) demand action here.
  • D — Disability (neurologic status). Rapid neuro check: level of consciousness via AVPU (Alert, responds to Voice, responds to Pain, Unresponsive) or the Glasgow Coma Scale, pupils (size, equality, reaction), and blood glucose (never miss hypoglycemia as a cause of altered mental status). A GCS of 8 or less generally signals the need to protect the airway.
  • E — Exposure and Environmental control. Fully expose the patient to find hidden injuries, rashes, or bleeding — then prevent hypothermia by covering with warm blankets. In trauma this includes logrolling to inspect the back. Exposure balances "find everything" against "keep the patient warm and dignified."

A useful memory aid for what actually kills, in order, is "the first thing that kills is airway, then breathing, then bleeding" — which is exactly why the letters run A, B, C.

The secondary survey begins only after the primary survey is complete and the patient is stabilized. It is the thorough phase: a focused history plus a complete head-to-toe examination to identify all injuries and problems that are not immediately life-threatening.

A widely taught history mnemonic is SAMPLE:

  • S — Signs and symptoms
  • A — Allergies
  • M — Medications
  • P — Past medical history / Pregnancy
  • L — Last oral intake
  • E — Events leading to the presentation

Pain is characterized with OPQRST (Onset, Provocation/palliation, Quality, Region/radiation, Severity, Timing). The head-to-toe exam inspects and palpates every region — head, face, neck, chest, abdomen, pelvis, extremities, back — plus a full set of vital signs, monitoring, and any indicated diagnostics. The core discipline to internalize: the secondary survey never comes before a stable primary survey, and any new instability sends you straight back to ABCDE.

Real-World Applications​

  • Waiting-room deterioration. A patient triaged as low acuity can worsen. Good nurses re-triage: reassessment intervals are built into every system precisely because a first impression can be wrong or the condition can evolve.
  • Trauma bay teamwork. ABCDE gives a multidisciplinary team a shared language — one person owns the airway, another circulation — so care is parallel and coordinated rather than everyone crowding the obvious wound.
  • Pre-hospital and disaster nursing. START tagging at a bus crash or during a hospital surge lets a single nurse impose order on dozens of casualties.
  • Rapid response / deteriorating ward patient. The ABCDE sweep is not just for the ED; it is the default framework for any acutely unwell patient anywhere in the hospital.

Common Mistakes​

  1. Fixing the dramatic injury first. Misconception: the most visible or gruesome problem (an open fracture, heavy scalp bleeding) is the priority. Why wrong: it violates the kill-order — a partly obstructed airway or tension pneumothorax will kill faster than a limb injury. Correction: always run A-B-C in order; distracting injuries are addressed in the secondary survey unless they cause airway/breathing/circulation failure.
  2. Treating hypotension as an early shock sign. Misconception: if blood pressure is normal, the patient is not in shock. Why wrong: young, healthy patients compensate; tachycardia, narrowing pulse pressure, cool skin, anxiety, and delayed capillary refill appear well before the BP drops. A falling BP is a late, ominous sign. Correction: act on the early signs of poor perfusion, not on the number alone.
  3. Skipping the glucose check in altered mental status. Misconception: confusion or unresponsiveness in the "D" step must be neurologic. Why wrong: hypoglycemia is a rapidly reversible, easily missed cause of altered consciousness. Correction: "Don't ever forget glucose" — check a bedside glucose in every patient with altered mental status.
  4. Over- or under-triage. Under-triage (assigning too low an acuity) risks missing time-critical illness; over-triage wastes scarce resources. Correction: use validated tools and when uncertain, triage up — err on the side of the patient's safety.

Comparison and Connections​

FeaturePrimary Survey (ABCDE)Secondary Survey
GoalFind and treat immediate life threatsIdentify all remaining injuries/problems
TimingFirst, before anything elseOnly after primary survey done and patient stable
SpeedSeconds to minutes, rapidMore thorough, detailed
MethodFixed A-B-C-D-E order; treat as you goHistory (SAMPLE/OPQRST) plus head-to-toe
Interruption ruleAny deterioration -> restart at AReturn to primary survey if instability arises

Triage answers who is seen first; the primary survey answers what is treated first once a patient is in front of you — related but distinct. START (mass-casualty) differs from everyday ESI/CTAS in its ethic: population benefit over individual maximal care. These skills connect closely to shock recognition and resuscitation (see ../../4._Medical_Surgical_Nursing/index.md) and to vital-signs and general assessment technique (see ../../2._Health_Assessment/index.md).

Practice Questions​

Recall​

Q: What do the letters in the primary survey ABCDE stand for, in order? A: Airway (with C-spine protection in trauma), Breathing, Circulation (with hemorrhage control), Disability (neurologic status), Exposure/Environment. The order reflects how quickly each problem is fatal.

Understanding​

Q: Why must the primary survey be completed before the secondary survey? A: The primary survey identifies and treats immediately life-threatening problems (airway obstruction, inadequate breathing, hemorrhagic shock). Doing a detailed head-to-toe exam first would waste minutes that could be fatal. Only once A-B-C-D-E threats are controlled is it safe to search for lower-priority injuries.

Application​

Q: Using ESI, how would you triage a patient with a simple medication refill request, normal vital signs, and no acute complaint? A: ESI-5 — the patient is stable and requires no ED resources (no labs, imaging, or procedures). They can safely wait longer while higher-acuity patients are seen.

Analysis​

Q: A trauma patient was assessed and found stable at "B." Midway through the secondary survey the nurse notes new restlessness, HR rising from 90 to 130, and cool skin. What should the nurse do and why? A: Stop the secondary survey and return to the primary survey, starting at A. The new tachycardia, restlessness, and poor perfusion suggest developing shock (circulation problem) or a compromised airway/breathing. The rule is that any deterioration triggers a fresh ABCDE reassessment; you re-verify airway and breathing before assuming it is purely circulatory, then look for occult hemorrhage or tension pneumothorax as a cause.

FAQ​

Is triage a nursing role, and can I get it "wrong"? Yes — triage is a core, autonomous nursing role in most emergency departments, usually requiring experience and specific training. Errors happen; the systems are designed to be reproducible and to be revisited through mandatory reassessment. When genuinely uncertain, triage the patient up to the safer level.

Do I always do the secondary survey? Not always fully. If the primary survey reveals an ongoing life threat you cannot stabilize (e.g., an unmanageable airway needing the OR), the patient may go to definitive care before a complete secondary survey. In stable patients, the secondary survey is standard.

What is the difference between AVPU and GCS? AVPU (Alert, Voice, Pain, Unresponsive) is a fast, four-point screen ideal for the rapid "D" step and pre-hospital use. The Glasgow Coma Scale is a more detailed 3-15 score (eye, verbal, motor) used for ongoing monitoring and trending. Both flag when a patient may not be protecting their airway (GCS 8 or less).

Why is hypotension called a "late sign" of shock? The body compensates for blood or fluid loss by increasing heart rate and constricting vessels, keeping blood pressure near normal until roughly 30 percent of blood volume is lost. So a "normal" BP can be falsely reassuring; by the time it drops, the patient is significantly compromised. Watch heart rate, skin, mental status, and capillary refill first.

How is disaster (START) triage ethically different from everyday triage? Everyday triage still aims to give each patient the best possible care, just in order of urgency. START, used when casualties overwhelm resources, aims for the greatest good for the greatest number — so a patient with unsurvivable injuries may be tagged "expectant" and receive only comfort measures so that recoverable patients can be saved. This shift is emotionally hard and is a recognized source of moral distress.

Where does cervical-spine protection fit in ABCDE? It is paired with "A" in trauma — you open and manage the airway while manually stabilizing the neck (jaw-thrust rather than head-tilt) whenever spinal injury is possible, because an airway maneuver must not worsen a potential spinal cord injury.

Quick Revision​

  • Triage = sorting by urgency when resources are limited; word from French trier, born on Napoleon's battlefields (Larrey).
  • Modern 5-level systems: ESI (US, acuity plus resources), CTAS (Canada, target times), MTS (UK, flowcharts); START for mass casualties (Red/Yellow/Green/Black).
  • ESI-1 = immediate life-saving intervention; ESI-2 = high-risk/dangerous; ESI-3/4/5 by resource count.
  • Primary survey = ABCDE, strict order, treat as you go: Airway, Breathing, Circulation, Disability, Exposure.
  • Deterioration = go back to A.
  • Secondary survey only after stabilization: SAMPLE history, OPQRST for pain, head-to-toe exam.
  • Hypotension is a late sign of shock; always check glucose in altered mental status; treat the killer, not the dramatic injury.

Prerequisites​

Next Topics​